Intel Core microarchitecture - AbsoluteAstronomy.com

The Intel Core microarchitecture (previously known as the Next-Generation Micro-Architecture, or NGMA) is a multi-core processor

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

microarchitecture

Microarchitecture

In computer engineering, microarchitecture , also called computer organization, is the way a given instruction set architecture is implemented on a processor. A given ISA may be implemented with different microarchitectures. Implementations might vary due to different goals of a given design or...

unveiled by Intel in Q1 2006. It is based around an updated version of the Yonah core and could be considered the latest iteration of the P6 microarchitecture

P6 (microarchitecture)

The P6 microarchitecture is the sixth generation Intel x86 microarchitecture, implemented by the Pentium Pro microprocessor that was introduced in November 1995. It is sometimes referred to as i686. It was succeeded by the NetBurst microarchitecture in 2000, but eventually revived in the Pentium M...

, which traces its history back to the Pentium Pro

Pentium Pro

The Pentium Pro is a sixth-generation x86 microprocessor developed and manufactured by Intel introduced in November 1, 1995 . It introduced the P6 microarchitecture and was originally intended to replace the original Pentium in a full range of applications...

introduced in 1995. The high power consumption and heat intensity of NetBurst-based processors, the resulting inability to effectively increase clock speed, and other bottlenecks such as the inefficient pipeline were the primary reasons Intel abandoned the NetBurst microarchitecture. The Core microarchitecture was designed by the Intel Israel (IDC) team that previously designed the Pentium M

Pentium M

The Pentium M brand refers to a family of mobile single-core x86 microprocessors introduced in March 2003 , and forming a part of the Intel Carmel notebook platform under the then new Centrino brand...

mobile processor .

The first processors that used this architecture were code-named Merom
Merom (microprocessor)
Merom is the code name for various Intel processors that are sold as Core 2 Duo, Core 2 Solo, Pentium Dual-Core and Celeron. It was the first mobile processor to be based on the Core microarchitecture, replacing the Enhanced Pentium M based Yonah processor. Merom has product code 80537, which is...

, Conroe
Conroe (microprocessor)
Conroe is the code name for many Intel processors sold as Core 2 Duo, Xeon, Pentium Dual-Core and Celeron. It was the first desktop processor to be based on the Core microarchitecture, replacing the NetBurst microarchitecture based Cedar Mill processor. It has product code 80557, which is shared...

, and Woodcrest; Merom is for mobile computing, Conroe is for desktop systems, and Woodcrest is for servers and workstations. While architecturally identical, the three processor lines differ in the socket used, bus speed, and power consumption. Mainstream Core-based processors are branded Pentium Dual-Core or Pentium
Pentium
The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...

and low end branded Celeron
Celeron
Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....

; server and workstation Core-based processors are branded Xeon
Xeon
The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...

, while desktop and mobile Core-based processors are branded as Core 2. Despite their names, processors sold as Core Solo/Core Duo and Core

Intel Core

Yonah was the code name for Intel's first generation of 65 nm process mobile microprocessors, based on the Banias/Dothan-core Pentium M microarchitecture. SIMD performance has been improved through the addition of SSE3 instructions and improvements to SSE and SSE2 implementations, while integer...

i3/i5/i7 do not actually use the Core microarchitecture and are based on the Enhanced Pentium M and newer Nehalem/Sandy Bridge

Sandy Bridge

Sandy Bridge is the codename for a microarchitecture developed by Intel beginning in 2005 for central processing units in computers to replace the Nehalem microarchitecture...

microarchitectures, respectively.

Features

The Core microarchitecture returned to lower clock rate

Clock rate

The clock rate typically refers to the frequency that a CPU is running at.For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wave...

s and improved the usage of both available clock cycles and power when compared with the preceding NetBurst microarchitecture of the Pentium 4

Pentium 4

Pentium 4 was a line of single-core desktop and laptop central processing units , introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a 7th-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the...

Pentium D

The Pentium D brand refers to two series of desktop dual-core 64-bit x86-64 microprocessors with the NetBurst microarchitecture manufactured by Intel. Each CPU comprised two dies, each containing a single core, residing next to each other on a multi-chip module package. The brand's first processor,...

-branded CPUs. The Core microarchitecture provides more efficient decoding stages, execution units, cache

CPU cache

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...

s, and buses, reducing the power consumption of Core 2-branded CPUs while increasing their processing capacity. Intel's CPUs have varied widely in power consumption according to clock rate, architecture, and semiconductor process, shown in the CPU power dissipation

CPU power dissipation

Central processing unit power dissipation or CPU power dissipation is the process in which central processing units consume electrical energy, and dissipate this energy both by the action of the switching devices contained in the CPU and by the energy lost in the form of heat due to the impedance...

tables.

Like the last NetBurst CPUs, Core based processors feature multiple cores and hardware virtualization support (marketed as Intel VT-x), as well as Intel 64 and SSSE3

SSSE3

Supplemental Streaming SIMD Extensions 3 is a SIMD instruction set created by Intel and is the fourth iteration of the SSE technology.- History :...

. However, Core-based processors do not have the Hyper-Threading Technology

Hyper-threading

Hyper-threading is Intel's term for its simultaneous multithreading implementation in its Atom, Intel Core i3/i5/i7, Itanium, Pentium 4 and Xeon CPUs....

found in Pentium 4 processors. This is because the Core microarchitecture is a descendant of the P6 microarchitecture

P6 (microarchitecture)

used by Pentium Pro, Pentium II, Pentium III, and Pentium M.

The L1 cache size was enlarged in the Core microarchitecture, from 32KB on Pentium II/III to 64 KB L1 cache/core (32 KB L1 Data + 32 KB L1 Instruction) on Pentium M and Core/Core 2. It also lacks an L3 Cache found in the Gallatin core of the Pentium 4 Extreme Edition, although an L3 Cache is present in high-end versions of Core-based Xeons. Both an L3 cache and Hyper-threading were reintroduced in the Nehalem microarchitecture.

Technology

The Intel Core Microarchitecture was designed from the ground up, but is similar to the Pentium M

Pentium M

microarchitecture in design philosophy. The Penryn

Penryn (microprocessor)

Penryn is the code name of a processor from Intel that is sold in varying configurations as Core 2 Solo, Core 2 Duo, Core 2 Quad, Pentium and Celeron....

pipeline is 14 stages long — less than half of Prescott's, a signature feature of wide order execution cores. Penryn's successor, Nehalem has 20-24 pipeline stages. Core's execution unit is 4 issues wide, compared to the 3-issue cores of P6

P6 (microarchitecture)

, Pentium M, and NetBurst microarchitectures. The new architecture is a dual core design with linked L1 cache and shared L2 cache engineered for maximum performance per watt

Performance per watt

In computing, performance per watt is a measure of the energy efficiency of a particular computer architecture or computer hardware. Literally, it measures the rate of computation that can be delivered by a computer for every watt of power consumed....

and improved scalability.

One new technology included in the design is Macro-Ops Fusion, which combines two x86 instructions into a single micro-operation

Micro-operation

In computer central processing units, micro-operations are detailed low-level instructions used in some designs to implement complex machine instructions .Various forms of μops have long been the basis for traditional microcode routines used to simplify the implementation of a...

. For example, a common code sequence like a compare followed by a conditional jump would become a single micro-op.

Other new technologies include 1 cycle throughput (2 cycles previously) of all 128-bit SSE instructions and a new power saving design. All components will run at minimum speed, ramping up speed dynamically as needed (similar to AMD's Cool'n'Quiet

Cool'n'Quiet

Cool'n'Quiet is a CPU speed throttling and power saving technology introduced by AMD with its Athlon 64 processor line. It works by reducing the processor's clock rate and voltage when the processor is idle. The aim of this technology is to reduce overall power consumption and lower heat...

power-saving technology, as well as Intel's own SpeedStep

SpeedStep

SpeedStep is a trademark for a series of dynamic frequency scaling technologies built into some Intel microprocessors that allow the clock speed of the processor to be dynamically changed by software...

technology from earlier mobile processors). This allows the chip to produce less heat, and consume as little power as possible.
For most Woodcrest CPUs, the front side bus (FSB)

Front side bus

A front-side bus is a computer communication interface often used in computers during the 1990s and 2000s.It typically carries data between the central processing unit and a memory controller hub, known as the northbridge....

runs at 1333 MT/s; however, this is scaled down to 1066 MT/s for lower end 1.60 and 1.86 GHz variants. The Merom mobile variant was initially targeted to run at a FSB of 667 MT/s while the second wave of Meroms, supporting 800 MT/s FSB, were released as part of the Santa Rosa platform with a different socket in May 2007. The desktop-oriented Conroe began with models having an FSB of 800 MT/s or 1066 MT/s with a 1333 MT/s line officially launched on July 22, 2007.

The power consumption of these new processors is extremely low—average use energy consumption is to be in the 1-2 watt range in ultra low voltage variants, with thermal design power

Thermal Design Power

The thermal design power , sometimes called thermal design point, refers to the maximum amount of power the cooling system in a computer is required to dissipate. For example, a laptop's CPU cooling system may be designed for a 20 watt TDP, which means that it can dissipate up to 20 watts of heat...

s (TDPs) of 65 watts for Conroe and most Woodcrests, 80 watts for the 3.0 GHz Woodcrest, and 40 watts for the low-voltage Woodcrest. In comparison, an AMD Opteron

Opteron

Opteron is AMD's x86 server and workstation processor line, and was the first processor which supported the AMD64 instruction set architecture . It was released on April 22, 2003 with the SledgeHammer core and was intended to compete in the server and workstation markets, particularly in the same...

875HE processor consumes 55 watts, while the energy efficient Socket AM2

Socket AM2

The Socket AM2, renamed from Socket M2 , is a CPU socket designed by AMD for desktop processors, including the performance, mainstream and value segments...

line fits in the 35 watt thermal envelope (specified a different way so not directly comparable). Merom, the mobile variant, is listed at 35 watts TDP for standard versions and 5 watts TDP for Ultra Low Voltage (ULV) versions.

Previously, Intel announced that it would now focus on power efficiency, rather than raw performance. However, at IDF

Intel Developer Forum

Intel Developer Forum , is a gathering of technologists to discuss Intel products and products based around Intel products. The first IDF was in 1997...

in the spring of 2006, Intel advertised both. Some of the promised numbers were:

20% more performance for Merom at the same power level (compared to Core Duo)
40% more performance for Conroe at 40% less power (compared to Pentium D
Pentium D
The Pentium D brand refers to two series of desktop dual-core 64-bit x86-64 microprocessors with the NetBurst microarchitecture manufactured by Intel. Each CPU comprised two dies, each containing a single core, residing next to each other on a multi-chip module package. The brand's first processor,...

)
80% more performance for Woodcrest at 35% less power (compared to the original dual-core Xeon)

Processor cores

The processors of the Core microarchitecture can be categorized by number of cores, cache size, and socket; each combination of these has a unique code name and product code that is used across a number of brands. For instance, code name "Allendale" with product code 80557 has two cores, 2 MB L2 cache and uses the desktop socket 775, but has been marketed as Celeron, Pentium, Core 2 and Xeon, each with different sets of features enabled. Most of the mobile and desktop processors come in two variants that differ in the size of the L2 cache, but the specific amount of L2 cache in a product can also be reduced by disabling parts at production time.
Wolfdale-DP and all quad-core processors except Dunnington QC are multi-chip modules combining two dies. For the 65 nm processors, the same product code can be shared by processors with different dies, but the specific information about which one is used can be derived from the stepping.

	fab	cores	\|Mobile	\|Desktop, UP Server	CL Server	DP Server	MP Server
Single-Core 65 nm	65 nm	1	Merom-L 80537		Conroe-L 80557
Single-Core 45 nm	45 nm	1		Penryn-L 80585				Wolfdale-CL 80588
Dual-Core 65 nm	65 nm	2	Merom-2M 80537	Merom 80537	Allendale 80557	Conroe 80557	Conroe-CL 80556	Woodcrest 80556	Tigerton-DC 80564
Dual-Core 45 nm	45 nm	2	Penryn-3M 80577	Penryn 80576	Wolfdale-3M 80571	Wolfdale 80570	Wolfdale-CL 80588	Wolfdale-DP 80573
Quad-Core 65 nm	65 nm	4				Kentsfield Kentsfield (microprocessor) Kentsfield is the code name of the first Intel desktop quad core CPU branded Core 2 , released on November 2, 2006. The top-of-the-line Kentsfields were Core 2 Extreme models numbered QX6xx0, while the mainstream ones branded Core 2 Quad were numbered Q6xx0. All of them featured two 4 MB L2... 80562		Clovertown 80563	Tigerton 80565
Quad-Core 45 nm	45 nm	4		Penryn-QC 80581	Yorkfield-6M 80580	Yorkfield 80569	Yorkfield-CL 80584	Harpertown 80574	Dunnington QC 80583
Six-Core 45 nm	45 nm	6							Dunnington 80582

Conroe/Merom (65 nm)

The original Core 2 processors are based around the same dies that can be identified as CPUID

CPUID

The CPUID opcode is a processor supplementary instruction for the x86 architecture. It was introduced by Intel in 1993 when it introduced the Pentium and SL-Enhanced 486 processors....

Family 6 Model 15. Depending on their configuration and packaging, their code names are Conroe (LGA 775, 4 MB L2 cache), Allendale (LGA 775, 2 MB L2 cache), Merom (Socket M

Socket M

Socket M is a CPU interface introduced by Intel in 2006 for the Intel Core line of mobile processors.-Technical specifications:Socket M is used in all Intel Core products, as well as the Core-derived Dual-Core Xeon codenamed Sossaman...

, 4 MB L2 cache) and Kentsfield (Multi-chip module

Multi-Chip Module

A multi-chip module is a specialized electronic package where multiple integrated circuits , semiconductor dies or other discrete components are packaged onto a unifying substrate, facilitating their use as a single component...

, LGA 775, 2x4MB L2 cache). Merom and Allendale processors with limited features can be found in Pentium Dual Core and Celeron

Celeron

Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....

processors,
while Conroe, Allendale and Kentsfield also are sold as Xeon

Xeon

The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...

processors.

Additional code names for processors based on this model are Woodcrest (LGA 771, 4 MB L2 cache), Clovertown (MCM, LGA 771, 2x4MB L2 cache) and Tigerton (MCM, Socket 604

Socket 604

Socket 604 is a 604 pin microprocessor socket designed to interface an Intel's Xeon processor to the rest of the computer. It provides both an electrical interface as well as physical support. This socket is designed to support a heatsink....

, 2x4MB L2 cache), all of which are marketed only under the Xeon brand.

Processor	Brand name	Model (list)	Cores	L2 Cache	Socket	TDP
Merom Merom (microprocessor) Merom is the code name for various Intel processors that are sold as Core 2 Duo, Core 2 Solo, Pentium Dual-Core and Celeron. It was the first mobile processor to be based on the Core microarchitecture, replacing the Enhanced Pentium M based Yonah processor. Merom has product code 80537, which is... -2M	Mobile Core 2 Duo	U7xxx	2	2 MiB	BGA479	10 W
Merom		L7xxx		4 MiB	BGA479	17 W
Merom Merom-2M		T5xxx T7xxx		2-4 MiB	Socket M Socket M Socket M is a CPU interface introduced by Intel in 2006 for the Intel Core line of mobile processors.-Technical specifications:Socket M is used in all Intel Core products, as well as the Core-derived Dual-Core Xeon codenamed Sossaman... Socket P Socket P The Intel Socket P is the mobile processor socket replacement for Core microarchitecture chips such as Core 2 Duo. It launched on May 9, 2007, as part of the Santa Rosa platform with the Merom and Penryn processors.-Technical specifications:... BGA479	35 W
Merom	Mobile Core 2 Extreme	X7xxx	2	4 MiB	Socket P	44 W
Merom	Celeron M	5x0	1	512 KiB	Socket M Socket P	30 W
Merom-2M	Celeron M	5x5	1	Socket P	Socket M Socket P	31 W
Merom-2M	Celeron Dual-Core	T1xxx	2	512-1024 KiB	Socket P	35 W
Merom-2M	Pentium Dual-Core	T2xxx T3xxx	2	1 MiB	Socket P	35 W
Allendale	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	3xxx	2	2 MB	LGA 775	65 W
Conroe Conroe (microprocessor) Conroe is the code name for many Intel processors sold as Core 2 Duo, Xeon, Pentium Dual-Core and Celeron. It was the first desktop processor to be based on the Core microarchitecture, replacing the NetBurst microarchitecture based Cedar Mill processor. It has product code 80557, which is shared...		3xxx	2	2-4 MB	LGA 775	65 W
Conroe and Allendale	Core 2 Duo	E4xxx	2	2 MB	LGA 775	65 W
Conroe and Allendale		E6xx0		2-4 MB	LGA 775
Conroe-CL		E6xx5		2-4 MB	LGA 771 LGA 771 LGA 771, also known as Socket J, is a CPU interface introduced by Intel in 2006. It is used in Intel Core microarchitecture based DP-capable server processors, the Dual-Core Xeon is codenamed Dempsey, Woodcrest, and Wolfdale and the Quad-Core processors Clovertown, Harpertown...
Conroe-XE	Core 2 Extreme	X6xxx	2	4 MB	LGA 775	75 W
Allendale	Pentium Dual-Core	E2xxx	2	1 MB	LGA 775	65 W
Allendale	Celeron Celeron Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....	E1xxx	2	512 KB	LGA 775	65 W
Kentsfield Kentsfield (microprocessor) Kentsfield is the code name of the first Intel desktop quad core CPU branded Core 2 , released on November 2, 2006. The top-of-the-line Kentsfields were Core 2 Extreme models numbered QX6xx0, while the mainstream ones branded Core 2 Quad were numbered Q6xx0. All of them featured two 4 MB L2...	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	32xx	4	2x4 MiB	LGA 775	95-105 W
Kentsfield	Core 2 Quad	Q6xxx	4	2x4 MiB	LGA 775	95-105 W
Kentsfield XE	Core 2 Extreme	QX6xxx	4	2x4 MiB	LGA 775	130 W
Woodcrest	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	51xx	2	4 MB	LGA 771	65-80 W
Clovertown		L53xx	4	2x4 MB	LGA 771	40-50 W
		E53xx				80 W
		X53xx				120-150 W
Tigerton-DC		E72xx	2	2x4 MB	Socket 604 Socket 604 Socket 604 is a 604 pin microprocessor socket designed to interface an Intel's Xeon processor to the rest of the computer. It provides both an electrical interface as well as physical support. This socket is designed to support a heatsink....	80 W
Tigerton		L73xx	4	2x4 MB		50 W
		E73xx		2x2-2x4 MB		80 W
		X73xx		2x4 MB		130 W

Conroe-L/Merom-L

The Conroe-L and Merom-L processors are based around the same core as Conroe and Merom, but only contain a single core and 1 MB of L2 cache, significantly reducing production cost and power consumption of the processor at the expense of performance compared to the dual-core version. It is used only in ultra-low voltage Core 2 Solo U2xxx and in Celeron processors and is identified as CPUID family 6 model 22.

Processor	Brand name	Model (list)	Cores	L2 Cache	Socket	TDP
Merom-L	Mobile Core 2 Solo	U2xxx	1	2 MiB	BGA479	5.5 W
Merom-L	Celeron M	5x0	1	512 KiB	Socket M Socket P	27 W
Merom-L	Celeron M	5x3	1	512-1024 KiB	BGA479	5.5-10 W
Conroe-L	Celeron M	4x0	1	512 KiB	LGA 775	35 W
Conroe-CL	Celeron M	4x5	1	512 KiB	LGA 771	65 W

Penryn/Wolfdale (45 nm)

In Intel's Tick-Tock

Intel Tick-Tock

"Tick-Tock" is a model, of Jones Farm 5 and adopted by chip manufacturer Intel Corporation since 2007 to follow every microarchitectural change with shrinking of the process technology. Every "tick" is a shrinking of process technology of the previous microarchitecture and every "tock" is a new...

cycle, the 2007/2008 "Tick" was the shrink of the Core microarchitecture to 45 nanometers as CPUID model 23. In Core 2 processors, it is used with the code names Penryn (Socket P), Wolfdale (LGA 775) and Yorkfield (MCM, LGA 775), some of which are also sold as Celeron, Pentium and Xeon processors. In the Xeon brand, the Wolfdale-DP and Harpertown code names are used for LGA 771 based MCMs with two or four active Wolfdale cores.

The chips come in two sizes, with 6 MB and 3 MB L2 cache. The smaller version is commonly called Penryn-3M and Wolfdale-3M as well as Yorkfield-6M, respectively. The single-core version of Penryn, listed as Penryn-L here, is not a separate model like Merom-L but a version of the Penryn-3M model with only one active core.

Processor	Brand name	Model (list)	Cores	L2 Cache	Socket	TDP
Penryn-L	Core 2 Solo	SU3xxx	1	3 MiB	BGA956	5.5 W
Penryn-3M	Core 2 Duo	SU7xxx	2	3 MB	BGA956	10 W
Penryn-3M		SU9xxx		3 MB		10 W
Penryn Penryn (microprocessor) Penryn is the code name of a processor from Intel that is sold in varying configurations as Core 2 Solo, Core 2 Duo, Core 2 Quad, Pentium and Celeron....		SL9xxx		6 MiB		17 W
		SP9xxx		6 MiB		25/28 W
Penryn-3M		P7xxx		3 MiB	Socket P Socket P The Intel Socket P is the mobile processor socket replacement for Core microarchitecture chips such as Core 2 Duo. It launched on May 9, 2007, as part of the Santa Rosa platform with the Merom and Penryn processors.-Technical specifications:... FCBGA6	25 W
Penryn-3M		P8xxx		3 MiB
Penryn		P9xxx		6 MiB
Penryn-3M		T6xxx		2 MiB		35 W
Penryn-3M		T8xxx		3 MiB
Penryn		T9xxx		6 MiB
Penryn		E8x35		6 MiB	Socket P	35-55 W
Penryn-QC	Core 2 Quad	Q9xxx	4	2x3-2x6 MiB	Socket P	45 W
Penryn XE	Core 2 Extreme	X9xxx	2	6 MiB	Socket P	44 W
Penryn-QC	Core 2 Extreme	QX9xxx	4	2x6 MiB	Socket P	45 W
Penryn-3M	Celeron Celeron Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....	T3xxx	2	1 MiB	Socket P	35 W
Penryn-3M		SU2xxx	2	1 MiB	µFC-BGA 956	10 W
Penryn-L		9x0	1	1 MiB	Socket P	35 W
Penryn-L		7x3	1	1 MiB	µFC-BGA 956	10 W
Penryn-3M	Pentium	T4xxx	2	1 MiB	Socket P	35 W
Penryn-3M		SU4xxx	2	2 MiB	µFC-BGA 956	10 W
Penryn-L		SU2xxx	1	2 MiB	µFC-BGA 956	5.5 W
Wolfdale-3M
	Celeron Celeron Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....	E3xxx	2	1 MB	LGA 775	65 W
	Pentium Pentium The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...	E2210		1 MB
		E5xxx		2 MB
		E6xxx		2 MB
	Core 2 Duo	E7xxx		3 MB
Wolfdale	Core 2 Duo	E8xxx		6 MB
Wolfdale	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	31x0				45-65 W
Wolfdale-CL		30x4	1		LGA 771 LGA 771 LGA 771, also known as Socket J, is a CPU interface introduced by Intel in 2006. It is used in Intel Core microarchitecture based DP-capable server processors, the Dual-Core Xeon is codenamed Dempsey, Woodcrest, and Wolfdale and the Quad-Core processors Clovertown, Harpertown...	30 W
Wolfdale-CL		31x3	2			65 W
Yorkfield Yorkfield (microprocessor) Yorkfield is the code name for some Intel processors sold as Core 2 Quad and Xeon.In Intel's Tick-Tock cycle, the 2007/2008 "Tick" was Penryn microarchitecture, the shrink of the Core microarchitecture to 45 nanometers as CPUID model 23, replacing Kentsfield, the previous model.Like its...	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	X33x0	4	2×3–2×6 MB	LGA 775	65–95 W
Yorkfield-CL		X33x3		2×3–2×6 MB	LGA 771 LGA 771 LGA 771, also known as Socket J, is a CPU interface introduced by Intel in 2006. It is used in Intel Core microarchitecture based DP-capable server processors, the Dual-Core Xeon is codenamed Dempsey, Woodcrest, and Wolfdale and the Quad-Core processors Clovertown, Harpertown...	80 W
Yorkfield-6M	Core 2 Quad	Q8xxx		2×2 MB	LGA 775	65–95 W
Yorkfield-6M		Q9x0x		2×3 MB
Yorkfield		Q9x5x		2×6 MB
Yorkfield XE	Core 2 Extreme	QX9xxx		2×6 MB		130–136 W
Yorkfield XE	Core 2 Extreme	QX9xx5		2×6 MB	LGA 771	150 W
Wolfdale-DP	Xeon	E52xx	2	6 MB	LGA 771	65 W
		L52xx				20-55 W
		X52xx				80 W
Harpertown		E54xx	4	2×6 MB	LGA 771	80 W
		L54xx				40-50 W
		X54xx				120-150 W

Dunnington

The Xeon "Dunnington" processor (CPUID Family 6, model 30) is closely related to Wolfdale but comes with six cores and an on-chip L3 cache and is designed for servers with Socket 604, so it is marketed only as Xeon, not as Core 2.

Processor	Brand name	Model (list)	Cores	L3 Cache	Socket	TDP
Dunnington	Xeon	E74xx	4-6	8-16 MB	Socket 604 Socket 604 Socket 604 is a 604 pin microprocessor socket designed to interface an Intel's Xeon processor to the rest of the computer. It provides both an electrical interface as well as physical support. This socket is designed to support a heatsink....	90 W
		L74xx	4-6	12 MB		50-65 W
		X7460	6	16 MB		130 W

Steppings

The Core microarchitecture uses a number of steppings, which unlike previous microarchitectures not only represent incremental improvements but also different sets of features like cache size and low power modes. Most of these steppings are used across brands, typically by disabling some of the features and limiting clock frequencies on low-end chips.

Steppings with a reduced cache size use a separate naming scheme, which means that the releases are no longer in alphabetic order. Additional steppings have been used in internal and engineering samples, but are not listed in the tables.

Many of the high-end Core 2 and Xeon processors use Multi-Chip Module

Multi-Chip Module

s of two or three chips in order to get larger cache sizes or more than two cores.

Steppings using 65 nm process

						Mobile (Merom Merom (microprocessor) Merom is the code name for various Intel processors that are sold as Core 2 Duo, Core 2 Solo, Pentium Dual-Core and Celeron. It was the first mobile processor to be based on the Core microarchitecture, replacing the Enhanced Pentium M based Yonah processor. Merom has product code 80537, which is... )			Desktop (Conroe Conroe (microprocessor) Conroe is the code name for many Intel processors sold as Core 2 Duo, Xeon, Pentium Dual-Core and Celeron. It was the first desktop processor to be based on the Core microarchitecture, replacing the NetBurst microarchitecture based Cedar Mill processor. It has product code 80557, which is shared... )				Desktop (Kentsfield Kentsfield (microprocessor) Kentsfield is the code name of the first Intel desktop quad core CPU branded Core 2 , released on November 2, 2006. The top-of-the-line Kentsfields were Core 2 Extreme models numbered QX6xx0, while the mainstream ones branded Core 2 Quad were numbered Q6xx0. All of them featured two 4 MB L2... )		Server (Woodcrest, Clovertown, Tigerton)
Stepping	Released	Area	CPUID	L2 cache	Max. clock	Celeron	Pentium	Core 2	Celeron	Pentium	Core 2	Xeon	Core 2	Xeon	Xeon
B2	Jul 2006	143 mm²	06F6	4 MiB	2.93 GHz	M5xx		T5000 T7000 L7000			E6000 X6000	3000			5100
B3	Nov 2006	143 mm²	06F7	4 MiB	3.00 GHz								Q6000 QX6000	3200	5300
L2	Jan 2007	111 mm²	06F2	2 MiB	2.13 GHz			T5000 U7000		E2000	E4000 E6000	3000
E1	May 2007	143 mm²	06FA	4 MiB	2.80 GHz	M5xx		T7000 L7000 X7000
G0	Apr 2007	143 mm²	06FB	4 MiB	3.00 GHz	M5xx		T7000 L7000 X7000		E2000	E4000 E6000	3000	Q6000 QX6000	3200	5100 5300 7200 7300
G2	Mar 2009	143 mm²	06FB	4 MiB	2.16 GHz	M5xx		T5000 T7000 L7000
M0	Jul 2007	111 mm²	06FD	2 MiB	2.40 GHz	5xx T1000	T2000 T3000	T5000 T7000 U7000	E1000	E2000	E4000
A1	Jun 2007	81 mm²	10661	1 MiB	2.20 GHz	M5xx		U2000	220 4x0

Steppings B2/B3, E1 and G0 of model 15 (cpuid 06fx) processors are evolutionary steps of the standard Merom/Conroe die with 4 MiB L2 cache, with the short-lived E1 stepping only being used in mobile processors. Stepping L2 and M0 are the "Allendale" chips with just 2 MiB L2 cache, reducing production cost and power consumption for low-end processors.

The G0 and M0 steppings improve idle power consumption in C1E state and add the C2E state in desktop processors. In mobile processors, all of which support C1 through C4 idle states, steppings E1, G0, and M0 add support for the Mobile Intel 965 Express (Santa Rosa) platform with Socket P

Socket P

The Intel Socket P is the mobile processor socket replacement for Core microarchitecture chips such as Core 2 Duo. It launched on May 9, 2007, as part of the Santa Rosa platform with the Merom and Penryn processors.-Technical specifications:...

, while the earlier B2 and L2 steppings only appear for the Socket M

Socket M

based Mobile Intel 945 Express (Napa refresh) platform.

The model 22 stepping A1 (cpuid 10661h) marks a significant design change, with just a single core and 1 MiB L2 cache further reducing the power consumption and manufacturing cost for the low-end. Like the earlier steppings, A1 is not used with the Mobile Intel 965 Express platform.

Steppings G0, M0 and A1 mostly replaced all older steppings in 2008. In 2009, a new stepping G2 was introduced to replace the original stepping B2.

Steppings using 45 nm process

						Mobile (Penryn Penryn (microprocessor) Penryn is the code name of a processor from Intel that is sold in varying configurations as Core 2 Solo, Core 2 Duo, Core 2 Quad, Pentium and Celeron.... )			Desktop (Wolfdale Wolfdale (microprocessor) Wolfdale is the code name for a processor from Intel that is sold in varying configurations as Core 2 Duo, Celeron, Pentium and Xeon. In Intel's Tick-Tock cycle, the 2007/2008 "Tick" was Penryn microarchitecture, the shrink of the Core microarchitecture to 45 nanometers as CPUID model 23... )				Desktop (Yorkfield Yorkfield (microprocessor) Yorkfield is the code name for some Intel processors sold as Core 2 Quad and Xeon.In Intel's Tick-Tock cycle, the 2007/2008 "Tick" was Penryn microarchitecture, the shrink of the Core microarchitecture to 45 nanometers as CPUID model 23, replacing Kentsfield, the previous model.Like its... )		Server (Wolfdale-DP, Harpertown, Dunnington)
Stepping	Released	Area	CPUID	L2 cache	Max. clock	Celeron Celeron Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....	Pentium Pentium The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...	Core 2	Celeron Celeron Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....	Pentium Pentium The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...	Core 2	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	Core 2	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...	Xeon Xeon The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...
C0	Nov 2007	107 mm²	10676	6 MiB	3.00 GHz			E8000 P7000 T8000 T9000 P9000 SP9000 SL9000 X9000			E8000	3100	QX9000		5200 5400
M0	Mar 2008	82 mm²	10676	3 MiB	2.40 GHz	7xx		SU3000 P7000 P8000 T8000 SU9000		E5000 E2000	E7000
C1	Mar 2008	107 mm²	10677	6 MiB	3.20 GHz								Q9000 QX9000	3300
M1	Mar 2008	82 mm²	10677	3 MiB	2.50 GHz								Q8000 Q9000	3300
E0	Aug 2008	107 mm²	1067A	6 MiB	3.33 GHz			T9000 P9000 SP9000 SL9000 Q9000 QX9000			E8000	3100	Q9000 Q9000S QX9000	3300	5200 5400
R0	Aug 2008	82 mm²	1067A	3 MiB	2.93 GHz	7xx 900 SU2000 T3000	T4000 SU2000 SU4000	SU3000 T6000 SU7000 P8000 SU9000	E3000	E5000 E6000	E7000		Q8000 Q8000S Q9000 Q9000S	3300
A1	Sep 2008	503 mm²	106D1	3 MiB	2.67 GHz										7400

In the model 23 (cpuid 01067xh), Intel started marketing stepping with full (6 MiB) and reduced (3 MiB) L2 cache at the same time, and giving them identical cpuid values. All steppings have the new SSE4.1

SSE4

SSE4 is a CPU instruction set used in the Intel Core microarchitecture and AMD K10 . It was announced on 27 September 2006 at the Fall 2006 Intel Developer Forum, with vague details in a white paper; more precise details of 47 instructions became available at the Spring 2007 Intel Developer Forum...

instructions. Stepping C1/M1 was a bug fix version of C0/M0 specifically for quad core processors and only used in those. Stepping E0/R0 adds two new instructions (XSAVE/XRSTOR) and replaces all earlier steppings.

In mobile processors, stepping C0/M0 is only used in the Intel Mobile 965 Express (Santa Rosa refresh) platform, whereas stepping E0/R0 supports the later Intel Mobile 4 Express (Montevina) platform.

Model 30 stepping A1 (cpuid 106d1h) adds an L3 cache as well as six instead of the usual two cores, which leads to an unusually large die size of 503 mm². As of February 2008, it has only found its way into the very high-end Xeon 7400 series (Dunnington).

Motherboard compatibility

Conroe, Conroe XE and Allendale all use Socket LGA 775; however, not every motherboard

Motherboard

In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

is compatible with these processors.

Supporting chipset

Chipset

A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...

s are:

Intel
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...

: 865G/PE/P, 945G/GZ/GC/P/PL, 965G/P, 975X, P/G/Q965, Q963, 946GZ/PL, P3x, G3x, Q3x, X38, X48, P4x , 5400 Express, Intel G31, G33 Chipsets
NVIDIA
NVIDIA
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...

: nForce4 Ultra/SLI X16
NForce4
The nForce4 is a motherboard chipset released by Nvidia in October, 2004. The chipset supports AMD 64-bit processors and Intel Pentium 4 LGA 775 processors.-nForce4/nForce4-4x:...

for Intel, nForce 570/590 SLI
NForce 500
The nForce 500 is a motherboard chipset series and the successor to the nForce4 series. It was revealed by NVIDIA on 2006-03-07 and released on 2006-05-23...

for Intel, nForce 650i Ultra/650i SLI/680i LT SLI/680i SLI
NForce 600
The nForce 600 chipset was released in the first half of November 2006, coinciding with the GeForce 8 series launch on November 8, 2006. The nForce 600 supports Intel's LGA 775 socket and AMD's Quad FX platform and replaces the nForce 500 series....

and nForce 750i SLI/780i SLI/790i SLI/790i Ultra SLI
NForce 700
The nForce 700 is a chipset series designed by Nvidia first released in December 2007. The series supports both Intel Core 2 and AMD Phenom processors, and replaces the nForce 600 series chipsets...

.
VIA
VIA Technologies
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...

: P4M800, P4M800PRO, P4M890, P4M900, PT880 Pro/Ultra, PT890.
SiS
Silicon Integrated Systems
Silicon Integrated Systems is a company that manufactures, among other things, motherboard chipsets. The company was founded in 1987 in Hsinchu Science Park, Taiwan.-Business:...

: 662, 671, 671fx, 672, 672fx
ATI
ATI Technologies
ATI Technologies Inc. was a semiconductor technology corporation based in Markham, Ontario, Canada, that specialized in the development of graphics processing units and chipsets. Founded in 1985 as Array Technologies Inc., the company was listed publicly in 1993 and was acquired by Advanced Micro...

: Radeon Xpress 200
Xpress 200
The Radeon Xpress 200 is a computer chipset released by ATI. The chipset supports AMD 64-bit processors as well as supporting Intel Pentium 4, Pentium D and Celeron processors...

and CrossFire Xpress 3200 for Intel

See also: List of Intel chipsets

The currently released Yorkfield XE model QX9770 (45 nm with 1600FSB) currently has limited chipset compatibility - with only X38, P35 (With Overclocking

Overclocking

Overclocking is the process of operating a computer component at a higher clock rate than it was designed for or was specified by the manufacturer, but some manufacturers purposely underclock their components to improve battery life. Many people just overclock or 'rightclock' their hardware to...

) and some high-performance X48 and P45 motherboards being compatible. BIOS updates are gradually being released to provide support for the new Penryn technology, and the new QX9775 is only compatible with D5400XS. The Wolfdale-3M model E7200 also has limited compatibility (at least the Xpress 200 chipset is incompatible).

Although a motherboard may have the required chipset to support Conroe, some motherboards based on the above mentioned chipsets do not support Conroe. This is because all Conroe-based processors require a new power delivery feature set specified in Voltage Regulator-Down (VRD) 11.0. This requirement is a result of Conroe's significantly lower power consumption, compared to the Pentium 4/D CPUs it is replacing. A motherboard that has both a supporting chipset and VRD 11 supports Conroe processors, but even then some boards will need an updated BIOS

BIOS

In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

to recognize Conroe's FID (Frequency ID) and VID (Voltage ID).

Synchronous memory modules

Unlike the previous Pentium 4

Pentium 4

and Pentium D

Pentium D

design, the Core 2 technology sees a greater benefit from memory running synchronously

Synchronization (computer science)

In computer science, synchronization refers to one of two distinct but related concepts: synchronization of processes, and synchronization of data. Process synchronization refers to the idea that multiple processes are to join up or handshake at a certain point, so as to reach an agreement or...

with the Front Side Bus

Front side bus

(FSB). This means that for the Conroe CPUs with FSB of 1066 MT/s, the ideal memory performance for DDR2 is PC2-8500. In a few configurations, using PC2-5300 instead of PC2-4200 can actually decrease performance. Only when going to PC2-6400 is there a significant performance increase. While DDR2 memory models with tighter timing specifications do improve performance, the difference in real world games and applications is often negligible.

Optimally, the memory bandwidth afforded should match the bandwidth of the FSB, that is to say that a CPU with a 533 MT/s rated bus speed should be paired with RAM matching the same rated speed, for example DDR2 533, or PC2-4200. A common myth is that installing interleaved RAM will offer double the bandwidth. This myth is false; at most the increase in bandwidth by installing interleaved RAM is roughly 5–10%. The AGTL+ PSB used by all NetBurst processors as well as current and medium-term (pre-QuickPath) Core 2 processors provide a 64-bit data path. Current chipsets provide for a couple of either DDR2 or DDR3 channels.

Matched processor and RAM ratings
Processor model	Front side bus	Matched memory and maximum bandwidth single channel / dual channel
Processor model	Front side bus	DDR	DDR2	DDR3
mobile: T5200, T5300, U2n00, U7n00	533 MT/s Megatransfer In computer technology, transfers per second and its more common derivatives gigatransfers per second and megatransfers per second are informal language that refer to the number of operations transferring data that occur in each second in some given data-transfer channel. It is also known as...	PC-3200 (DDR-400) 3.2 GB/s	PC2-4200 (DDR2-533) 4.264 GB/s PC2-8500 (DDR2-1066) 8.532 GB/s	PC3-8500 (DDR3-1066) 8.530 GB/s
desktop: E6n00, E6n20, X6n00, E7n00, Q6n00 and QX6n00 mobile: T9400, T9550, T9600, P7350, P7450, P8400, P8600, P8700, P9500, P9600, SP9300, SP9400, X9100	1066 MT/s	PC-3200 (DDR-400) 3.2 GB/s		PC3-8500 (DDR3-1066) 8.530 GB/s
mobile: T5n00, T5n50, T7n00 (Socket M Socket M Socket M is a CPU interface introduced by Intel in 2006 for the Intel Core line of mobile processors.-Technical specifications:Socket M is used in all Intel Core products, as well as the Core-derived Dual-Core Xeon codenamed Sossaman... ), L7200, L7400	667 MT/s	PC-3200 (DDR-400) 3.2 GB/s	PC2-5300 (DDR2-667) 5.336 GB/s	PC3-10600 (DDR3-1333) 10.670 GB/s
desktop: E6n40, E6n50, E8nn0, Q9nn0, QX6n50, QX9650	1333 MT/s	PC-3200 (DDR-400) 3.2 GB/s	PC2-5300 (DDR2-667) 5.336 GB/s	PC3-10600 (DDR3-1333) 10.670 GB/s
mobile: T5n70, T6400, T7n00 (Socket P Socket P The Intel Socket P is the mobile processor socket replacement for Core microarchitecture chips such as Core 2 Duo. It launched on May 9, 2007, as part of the Santa Rosa platform with the Merom and Penryn processors.-Technical specifications:... ), L7300, L7500, X7n00, T8n00, T9300, T9500, X9000 desktop: E4n00, Pentium E2nn0, Pentium E5nn0, Celeron 4n0, E3n00	800 MT/s	PC-3200 (DDR-400) 3.2 GB/s PC-3200 (DDR-400) 3.2 GB/s	PC2-6400 (DDR2-800) 6.400 GB/s PC2-8500 (DDR2-1066) 8.532 GB/s	PC3-6400 (DDR3-800) 6.400 GB/s PC3-12800 (DDR3-1600) 12.800 GB/s
desktop: QX9770, QX9775	1600 MT/s	PC-3200 (DDR-400) 3.2 GB/s PC-3200 (DDR-400) 3.2 GB/s

On jobs requiring large amounts of memory access, the quad-core Core 2 processors can benefit significantly from using a PC2-8500 memory, which runs exactly the same speed as the CPU's FSB; this is not an officially supported configuration, but a number of motherboards offer it.

The Core 2 processor does not require the use of DDR2. While the Intel 975X and P965 chipsets require this memory, some motherboards and chipsets support both the Core 2 and DDR

DDR SDRAM

Double data rate synchronous dynamic random access memory is a class of memory integrated circuits used in computers. DDR SDRAM has been superseded by DDR2 SDRAM and DDR3 SDRAM, neither of which are either forward or backward compatible with DDR SDRAM, meaning that DDR2 or DDR3 memory modules...

memory. When using DDR memory, performance may be reduced because of the lower available memory bandwidth.

Chip errata

The Core 2 memory management unit

Memory management unit

A memory management unit , sometimes called paged memory management unit , is a computer hardware component responsible for handling accesses to memory requested by the CPU...

(MMU) in X6800, E6000 and E4000 processors does not operate to previous specifications implemented

Implementation

Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy.-Computer Science:...

in previous generations of x86 hardware. This may cause problems, many of them serious security and stability issues, with existing operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

software. Intel's documentation states that their programming manuals will be updated "in the coming months" with information on recommended methods of managing the translation lookaside buffer

Translation Lookaside Buffer

A translation lookaside buffer is a CPU cache that memory management hardware uses to improve virtual address translation speed. All current desktop and server processors use a TLB to map virtual and physical address spaces, and it is ubiquitous in any hardware which utilizes virtual memory.The...

(TLB) for Core 2 to avoid issues, and admits that, "in rare instances, improper TLB invalidation may result in unpredictable system behavior, such as hangs or incorrect data."

Among the issues noted:

Non-execute
NX bit
The NX bit, which stands for No eXecute, is a technology used in CPUs to segregate areas of memory for use by either storage of processor instructions or for storage of data, a feature normally only found in Harvard architecture processors...

bit is shared across the cores.
Floating point instruction non-coherencies.
Allowed memory corruptions outside of the range of permitted writing for a process by running common instruction sequences.

Intel errata

Erratum

An erratum or corrigendum is a correction of a book. An erratum is most commonly issued shortly after its original text is published. Patches to security issues in a computer program are also sometimes called errata. As a general rule, publishers issue an erratum for a production error An erratum...

Ax39, Ax43, Ax65, Ax79, Ax90, Ax99 are said to be particularly serious. 39, 43, 79, which can cause unpredictable behavior or system hang, have been fixed in recent steppings.

Among those who have noted the errata to be particularly serious are OpenBSD

OpenBSD

OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...

's Theo de Raadt

Theo de Raadt

Theo de Raadt , born May 19, 1968 in Pretoria, South Africa, is a software engineer who lives in Calgary, Alberta, Canada. He is the founder and leader of the OpenBSD and OpenSSH projects, and was a founding member of the NetBSD project.- Childhood :...

and DragonFly BSD

DragonFly BSD

DragonFly BSD is a free Unix-like operating system created as a fork of FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and a FreeBSD developer between 1994 and 2003, began work on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on July...

's Matthew Dillon

Matt Dillon (computer scientist)

Matthew Dillon is a computer scientist living in Berkeley, California. He is best known for his contributions to FreeBSD and for starting the DragonFly BSD project....

. Taking a contrasting view was Linus Torvalds

Linus Torvalds

Linus Benedict Torvalds is a Finnish software engineer and hacker, best known for having initiated the development of the open source Linux kernel. He later became the chief architect of the Linux kernel, and now acts as the project's coordinator...

, calling the TLB issue "totally insignificant", adding, "The biggest problem is that Intel should just have documented the TLB behavior better."

Microsoft has issued update KB936357 to address the errata by microcode

Microcode

Microcode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high-speed memory and translates machine instructions into sequences of detailed...

update, with no performance penalty. BIOS updates are also available to fix the issue.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.